In his analysis, ABC News' Polling Director Gary Langer writes, "Skepticism about Sarah Palin has soared since she entered the national political stage, with six in 10 Americans now doubting her qualifications for office and fewer than half convinced of her grasp of complex issues."

Ifil told the Associated Press in an interview yesterday that she hasn't yet written the chapter on Obama.

On Good Morning America Thursday, ABC News' Chief Washington Correspondent George Stephanopoulos said the debate stakes are high for the Alaska governor tonight and blogged, "Any mistake or gaffe by Palin could be fatal with a new poll finding voters are now questioning their commitment to Republican presidential candidate John McCain because of her."

Also on Good Morning America, ABC's Kate Snow previewed the preparation efforts of both candidates.

Sen. Joe Biden has been practicing this week in Delaware with Michigan Gov. Jennifer Granholm, taking advice from female Democratic Senate colleagues about how to go up against Palin, while politicos on both sides of the aisle examine his propensity for verbosity and slip-ups.

Palin -- who's been preparing for the debate from McCain's Sedona ranch this week with a mix of readings, oral briefings and practice -- said she'll go after Biden on taxes and troop funding, potentially using the Delaware senator's own words against him. In May 2007, Biden called a vote by running mate Barack Obama against reauthorizing funding for troops in Iraq "reckless" and "irresponsible" and "so political."

Before the Biden-Palin debate, of course, there was the highly-anticipated face-off of 1984 between then-Vice President George H.W. Bush and Democratic vice presidential candidate Geraldine Ferraro. Check out the World News coverage of that debate here!

For a walk down memory lane (presidential debate edition), check out this video produced by ABCNews.com producer Lindsey Ellerson on memorable debate moments in the election cycles of yore.